import jakarta.servlet.ServletContext;
import jakarta.servlet.http.HttpSessionEvent;
import jakarta.servlet.http.HttpSessionListener;



public class MyListener implements HttpSessionListener {
    public void sessionCreated(HttpSessionEvent se) {
        int online = 0;
        ServletContext context = se.getSession().getServletContext();
        if (context.getAttribute("ol") != null) {
            online = online+1;
            context.setAttribute("ol", online);
        }else {
            online =(int)context.getAttribute("ol");
            online++;
            context.setAttribute("ol", online);
        }
    }
    public void sessionDestroyed(HttpSessionEvent se) {
        ServletContext context = se.getSession().getServletContext();
        int online= (int)context.getAttribute("ol");
        online--;
        context.setAttribute("ol", online);
    }
}
